Pedal operated watercraft, such as canoes, are well known in the art and there are numerous patents directed to specific features thereof. Such devices generally comprise a frame structure, with or without a seat, having a pedal crank and sprocket system connected, by way of a chain, to a drive shaft which drives, via a series of gears and pinions, a vertically mounted drive shaft at the stern of the watercraft which in turn drives a propeller mounted on a horizontal axis. Such devices are relatively complex and involve a long gear train which is inherently expensive. The rigidly mounted vertical shaft at the stern to drive the propeller implies that the propeller is at a fixed depth relative to the keel of the watercraft, and it is difficult, if not impossible, for a canoeist to turn around in a relatively unstable canoe to reach the vertically mounted drive shaft at the stern so as to raise the propeller out of the water when not in use or in shallow water. There is a need, therefore, for a simple pedal operated propulsion system in which the propeller can be raised or lowered easily by the canoeist without moving from his seat or even turning to face the rear of the canoe. Preferably, the canoeist should be seated as low as possible in the canoe for stability reasons and the pedal device should incorporate both the seat and the crank mechanism and should be simply placed across the gunwhales of the canoe without needing clamps, bolts or other devices to secure it in place.